Peripheral oedema as an adverse effect of treatment of secondary progressive multiple sclerosis with siponimod: A case series

Siponimod is a sphingosine 1-phosphate receptor (S1P) modulator used to treat secondary progressive multiple sclerosis (SPMS). We report 3 SPMS patients treated with siponimod who developed new or worsening peripheral oedema soon after commencing treatment. In one case, peripheral oedema resulted in immobility. Siponimod-related peripheral oedema deserves wider recognition due to the potential for morbidity and over-investigation. Clinicians should assess for pre-existing oedema and coexisting conditions that may predispose to developing peripheral oedema prior to commencing siponimod.

Dos and don’ts for achieving managerial diversity Frank Dobbin and Alexandra Kalev Belknap Press, 2022. 272 pp

A pair of sociologists turn to data to determine how to diversify organizations’ upper ranks

A field experiment on subgoal framing to boost volunteering: The trade-off between goal granularity and flexibility

Research suggests that breaking overarching goals into more granular subgoals is beneficial for goal progress. However, making goals more granular often involves reducing the flexibility provided to complete them, and recent work shows that flexibility can also be beneficial for goal pursuit. We examine this trade-off between granularity and flexibility in subgoals in a preregistered, large-scale field experiment (N = 9,108) conducted over several months with volunteers at a national crisis counseling organization. A preregistered vignette pilot study (N = 900) suggests that the subgoal framing tested in the field could benefit goal seekers by bolstering their self-efficacy and goal commitment, and by discouraging procrastination. Our field experiment finds that reframing an overarching goal of 200 hr of volunteering into more granular subgoals (either 4 hr of volunteering every week or 8 hr every 2 weeks) increased hours volunteered by 8% over a 12-week period. Further, increasing subgoal flexibility by breaking an annual 200-hr volunteering goal into a subgoal of volunteering 8 hr every 2 weeks, rather than 4 hr every week, led to more durable benefits. (PsycInfo Database Record (c) 2023 APA, all rights reserved).

Autonomy in the Operating Room: A Multicenter Study of Gender Disparities During Surgical Training

BACKGROUND

Gender disparities are prevalent in medicine, but their impact on surgical training is not well studied.

OBJECTIVE

To quantify gender disparities in trainee intraoperative experiences and explore the variables associated with ratings of surgical autonomy and performance.

METHODS

From September 2015 to May 2019, attending surgeons and trainees from 71 programs assessed trainee autonomy on a 4-level Zwisch scale and performance on a 5-level modified Dreyfus scale after surgical procedures. Multivariable regression models were used to examine the association of trainee gender with autonomy and performance evaluations.

RESULTS

A total of 3255 trainees and attending surgeons completed 94 619 evaluations. Attendings gave lower ratings of operative autonomy to female trainees than male trainees when controlling for training level, attending, and surgical procedure (effect size B = -0.0199, P = .008). There was no difference in ratings of autonomy at the beginning of training (P = .32); the gap emerged as trainees advanced in years (B = -0.0163, P = .020). The gender difference in autonomy was largest for the most complex cases (B = -0.0502, P = .002). However, there was no difference in attending ratings of surgical performance for female trainees compared to male trainees (B = -0.0124, P = .066). Female trainees rated themselves as having less autonomy and worse performance than males when controlling for training level, attending, procedure, case complexity, and attending ratings (autonomy B = -0.0669, P < .001; performance B = -0.0704, P < .001).

CONCLUSIONS

While there was no significant difference in ratings of operative performance, a small difference between ratings of operative autonomy for female and male surgical trainees was identified.

Obesity and surgical complications of pancreaticoduodenectomy: An observation study utilizing ACS NSQIP

BACKGROUND

An estimated 38% of US adults are obese. Obesity is associated with socioeconomic disparities and increased rates of comorbidities, and is a known risk factor for development of pancreatic cancer. As a fourth leading cause of death in the United States, pancreatic cancer is commonly treated with a pancreatico-duodenectomy (PD), or Whipple procedure. Data regarding the effects of obesity on post-operative complication rate primarily comes from specialized centers, however the results are mixed. Our aim is to elucidate the effects that obesity has on outcomes after PD for pancreatic head cancer using a national prospectively maintained clinical database.

METHOD

The 2010-2015 American College of Surgeons National Surgical Quality Improvement Project (ACS NSQIP) Participant Use Files (PUF) were used as the data source. We identified cases in which PD was performed (CPT code 48150) in the setting of a postoperative diagnosis of pancreatic cancer (ICD9 code 157.0). We excluded cases that had emergency admissions, BMI ≤18.5 kg/m², intraoperative wound classification of III or IV, and disseminated cancer. Cases with missing BMI, preoperative albumin, operative time, LOS data were also excluded. Multiple imputation for missing sex, race, functional status, and ASA classification using chained equations was performed.¹⁶ Patients that had BMI ≥30 kg/m² were considered obese, and patients with BMI <30 kg/m² were used as control.

RESULTS

3484 patients underwent pancreaticoduodenectomy for pancreatic cancer. 860 patients were identified as obese. Propensity score analysis was performed matching age, sex, race, functional status, presence of dyspnea, diabetes, hypertension, acute renal failure, dialysis dependence, ascites, steroid use, bleeding disorders, history of chronic obstructive pulmonary disease (COPD), congestive heart failure (CHF), weight loss, American Society of Anesthesiologists (ASA) classification, and preoperative albumin levels. After matching, obese patients had higher risk of 30-day postoperative complications compared to control, including organ space wound infections (OR 1.38, 95% CI 1.07-1.79, p = 0.0128), returning to the operating room (OR 1.39, 95% CI 1.01-1.91, p = 0.0461), failure to extubate for greater than 48 h (OR 1.60, 95% CI 1.09-2.34, p = 0.0153), death (OR 1.68, 95% CI 1.01-2.78, p = 0.0453), septic shock (OR 2.22, 95% CI 1.46-3.38, p = 0.0002), pulmonary embolism (OR 2.42, 95% CI 1.07-5.45, p = 0.0332), renal insufficiency (OR 2.67, 95% CI 1.33-5.38, p = 0.0058). Sensitivity analysis yielded similar results with the exception of risk for return to the operating room, death, and pulmonary embolism, P > .05.

CONCLUSION

In this large observational study using a national clinical database, obese patients undergoing PD for head of pancreas cancer had increased risk of postoperative complications and mortality in comparison to controls.

Single point mutation on the gene encoding dysbindin results in recognition deficits

The dystrobrevin-binding protein 1 (DTNBP1) gene is a candidate risk factor for schizophrenia and has been associated with cognitive ability in both patient populations and healthy controls. DTNBP1 encodes dysbindin protein, which is localized to synaptic sites and is reduced in the prefrontal cortex and hippocampus of patients with schizophrenia, indicating a potential role in schizophrenia etiology. Most studies of dysbindin function have focused on the sandy (sdy) mice that lack dysbindin protein and have a wide range of abnormalities. In this study, we examined dysbindin salt and pepper (spp) mice that possess a single point mutation on the Dtnbp1 gene predicted to reduce, but not eliminate, dysbindin expression. By western blot analysis, we found that spp homozygous (spp -/-) mutants had reduced dysbindin and synaptosomal-associated protein 25 (SNAP-25) in the prefrontal cortex, but unaltered levels in hippocampus. Behaviorally, spp mutants performed comparably to controls on a wide range of tasks assessing locomotion, anxiety, spatial recognition and working memory. However, spp -/- mice had selective deficits in tasks measuring novel object recognition and social novelty recognition. Our results indicate that reduced dysbindin and SNAP-25 protein in the prefrontal cortex of spp -/- is associated with selective impairments in recognition processing. These spp mice may prove useful as a novel mouse model to study cognitive deficits linked to dysbindin alterations. Our findings also suggest that aspects of recognition memory may be specifically influenced by DTNBP1 single nucleotide polymorphisms or risk haplotypes in humans and this connection should be further investigated.

Transferrin receptor targeting nanomedicine delivering wild-type p53 gene sensitizes pancreatic cancer to gemcitabine therapy

To overcome gene therapy barriers such as low transfection efficiency and nonspecific delivery, liposomal nanoparticles targeted by a single-chain antibody fragment to the transferrin receptor (TfRscFv) delivering wild-type (wt) human p53 (SGT-53) were developed for tumor-specific targeting. We hypothesize that SGT-53 in combination with gemcitabine will demonstrate enhanced therapeutic benefit in an in vivo metastatic pancreatic cancer model. Intrasplenic injection of 1 × 10(6) Panc02 murine pancreatic cancer cells was used to generate in vivo hepatic metastatic tumors. Nanoparticle localization was assessed by tail vein injection of TfRscFv with fluorescently labeled oligonucleotides (6-carboxyfluorescein phosphoramidite (6FAM) ODN) imaged by Xenogen IVIS 200 scan. SGT-53 (equivalent to 30 μg of p53 intravenously) and gemcitabine (20 mg/kg intraperitoneally) alone and in combination were administered biweekly and compared with untreated mice. Survival was determined by blinded daily assessment of morbidity. Human wtp53 expression and transferrin levels in the tumors were assessed by western blot analysis. Tumor burden was quantified by liver weight. Xenogen imaging demonstrated tumor-specific uptake of TfRscFv-6FAM ODN. Exogenous human wtp53 protein was detected in the SGT-53-treated tumors compared with control. Compared with untreated mice with metastatic tumors demonstrating median survival of 20 days, SGT-53, gemcitabine and the combination demonstrated improved median survival of 29, 30 and 37 days, respectively. The combination treatment prolonged median survival when compared with single drug treatment and decreased tumor burden. The tumor targeting liposomal-based SGT-53 nanoparticle is capable of sensitizing pancreatic cancer to conventional chemotherapy in pancreatic cancer models. This approach has the potential to be translated into a new, more effective therapy for pancreatic cancer. Further optimization is ongoing, moving towards a Phase 1B/2 clinical trial.

Physical characterization methods for iron oxide contrast agents encapsulated within a targeted liposome-based delivery system

Intact liposome-based targeted nanoparticle delivery systems (NDS) are immobilized by non-selective binding and characterized by scanning probe microscopy (SPM) in a fluid imaging environment. The size, size distribution, functionality, and stability of an NDS with a payload consisting of a super-paramagnetic iron oxide contrast agent for magnetic resonance imaging are determined. SPM results are combined with information obtained by more familiar techniques such as superconducting quantum interference device (SQUID) magnetometry, dynamic light scattering, and electron microscopy. By integrating the methods presented in this work into the NDS formulation and manufacturing process, size-dependent statistical properties of the complex can be obtained and the structure-function relationship of individual, multi-component nanoscale entities can be assessed in a reliable and reproducible manner.

A sterically stabilized immunolipoplex for systemic administration of a therapeutic gene

A sterically stabilized immunolipoplex (TsPLP), containing an antitransferrin receptor single-chain antibody fragment (TfRscFv)-PEG molecule, has been developed to specifically and efficiently deliver a therapeutic gene to tumor cells. A postcoating preparation strategy was employed in which a DNA/lipid complex (lipoplex) was formed first and then sequentially conjugated with PEG and TfRscFv. The complex prepared by this method was shown to be superior in ability to deliver genes to tumor cells than when prepared by a common precoating strategy, in which DNA is mixed with TfRscFv-PEG conjugated liposome. Using prostate cancer cell line DU145, a comparison was made between the in vitro and in vivo gene delivery efficiencies of four complexes, Lipoplex (LP), PEG-Lipoplex (PLP), TfRscFv-PEG-Lipoplex (TsPLP) and our standard TfRscFv-Lipoplex (TsLP). In vitro, the order of transfection efficiency was TsLP>LP approximately TsPLP>PLP. However, in vivo the order of transfection efficiency, after systemic administration via the tail vein, was TsPLP>TsLP>LP or PLP with TsPLP-mediated exogenous gene expression in tumor being two-fold higher than when mediated by TsLP. This suggests that the in vitro transfection efficiency of TsPLP was not indicative of its in vivo efficiency. In addition, it was found that the level of exogenous gene expression in the tumor mediated by TsPLP was higher than that mediated by TsLP and did not decrease over the time. More importantly, high exogenous gene expression in tumor, but low expression in liver, was observed after an i.v. delivery of TsPLP carrying either the GFP reporter gene or the p53 gene, indicating that tumor preferential targeting was maintained by this complex in the presence of PEG. These findings show that incorporation of PEG into our targeted lipoplex results in a more efficient delivery of the complex to the tumor cells, possibly by inhibiting the first pass clearance observed with non-PEG containing liposomes. Therefore, these data demonstrate that TsPLP is a improvement over our previously established tumor targeted gene delivery complex for systemic gene therapy of cancer.

Inhibitory effects of the combination of HER-2 antisense oligonucleotide and chemotherapeutic agents used for the treatment of human breast cancer

Poor response to chemotherapy in patients with breast cancer is often associated with overexpression of HER-2/neu. Interference with HER-2 mRNA translation by means of antisense oligonucleotides might improve the efficacy of chemotherapy. To test this hypothesis, eight breast cancer cell lines and a normal human fibroblast cell line were examined for their level of HER-2 expression, their sensitivity to phosphorothioate antisense oligonucleotides (AS HER-2 ODN), and to various chemotherapeutic agents, and the combination of the two. No correlation was found between the intrinsic HER-2 level and either the sensitivity to a particular chemotherapeutic agent alone, or the amount of growth inhibition observed with a specific AS HER-2 ODN concentration. Although sequence specificity and extent of AS HER-2 ODN inhibition of HER-2 synthesis were somewhat higher in the HER-2 overexpressing MDA-MB-453 and SK-BR-3 cells, we found that antisense treatment significantly sensitized all of the breast cancer cells, even MDA-MB-231 and MDA-MB-435 cells, with approximately basal levels of HER-2, to various chemotherapeutic agents. In addition, the combination of AS HER-2 ODN and taxol was shown to synergistically induce apoptosis in MDA-MB-435. These results demonstrate that overexpression of HER-2 would not be a prerequisite for the effective use of AS HER-2 ODN as a combination treatment modality for breast cancer and suggest that the use of AS HER-2 ODN, as part of a combination treatment modality, need not be limited to breast tumors that display elevated levels of HER-2.

Systemic p53 gene therapy of cancer with immunolipoplexes targeted by anti-transferrin receptor scFv

BACKGROUND

A long-standing goal in genetic therapy for cancer is a systemic gene delivery system that selectively targets tumor cells, including metastases. Here we describe a novel cationic immunolipoplex system that shows high in vivo gene transfer efficiency and anti- tumor efficacy when used for systemic p53 gene therapy of cancer.

MATERIALS AND METHODS

A cationic immunolipoplex incorporating a biosynthetically lipid-tagged, anti-transferrin receptor single-chain antibody (TfRscFv), was designed to target tumor cells both in vitro and in vivo. A human breast cancer metastasis model was employed to evaluate the in vivo efficacy of systemically administered, TfRscFv-immunolipoplex-mediated, p53 gene therapy in combination with docetaxel.

RESULTS

The TfRscFv-targeting cationic immunolipoplex had a size of 60-100 nm, showed enhanced tumor cell binding, and improved targeted gene delivery and transfection efficiencies, both in vitro and in vivo. The p53 tumor suppressor gene was not only systemically delivered by the immunolipoplex to human tumor xenografts in nude mice but also functionally expressed. In the nude mouse breast cancer metastasis model, the combination of the p53 gene delivered by the systemic administration of the TfRscFv-immunolipoplex and docetaxel resulted in significantly improved efficacy with prolonged survival.

CONCLUSIONS

This is the first report using scFv-targeting immunolipoplexes for systemic gene therapy. The TfRscFv has a number of advantages over the transferrin (Tf) molecule itself: (1) scFv has a much smaller size than Tf producing a smaller immunolipoplex giving better penetration into solid tumors; (2) unlike Tf, the scFv is a recombinant protein, not a blood product; (3) large scale production and strict quality control of the recombinant scFv, as well as scFv-immunolipoplex, are feasible. The sensitization of tumors to chemotherapy by this tumor-targeted and efficient p53 gene delivery method could lower the effective dose of the drug, correspondingly lessening the severe side effects, while decreasing the possibility of recurrence. Moreover, this approach is applicable to both primary and recurrent tumors, and more significantly, metastatic disease. The TfRscFv-targeting of cationic immunolipoplexes is a promising method of tumor targeted gene delivery that can be used for systemic gene therapy of cancer with the potential to critically impact the clinical management of cancer.

Downmodulation of bFGF-binding protein expression following restoration of p53 function

Angiogenesis is a requirement for solid tumor growth. Therefore, inhibition of this neovascularization is one mechanism by which restoration of wtp53 function may lead to tumor regression. Here we report that adenoviral vector-mediated wild-type p53 transduction results in growth inhibition of squamous cell carcinoma of the head and neck tumor cells both in vitro and in a xenograft mouse model. This growth inhibition is associated with the down-regulation of the expression of fibroblast growth factor binding protein, a secreted protein required for the activation of angiogenic factor basic FGF. These findings suggest that wtp53-induced tumor regression is due, at least in part, to antiangiogenesis mediated by the downmodulation of fibroblast growth factor binding protein.

Tumor-targeted p53-gene therapy enhances the efficacy of conventional chemo/radiotherapy

A long-standing goal in gene therapy for cancer is a stable, low toxic, systemic gene delivery system that selectively targets tumor cells, including metastatic disease. Progress has been made toward developing non-viral, pharmaceutical formulations of genes for in vivo human therapy, particularly cationic liposome-mediated gene transfer systems. Ligand-directed tumor targeting of cationic liposome-DNA complexes (lipoplexes) is showing promise for targeted gene delivery and systemic gene therapy. Lipoplexes directed by ligands such as folate, transferrin or anti-transferrin receptor scFv, showed tumor-targeted gene delivery and expression in human breast, prostate, head and neck cancers. The two elements, ligand/receptor and liposome composition, work together to realize the goal of functional tumor targeting of gene therapeutics. The tumor suppressor gene, p53, has been shown to be involved in the control of DNA damage-induced apoptosis. Loss or malfunction of this p53-mediated apoptotic pathway has been proposed as one mechanism by which tumors become resistant to chemotherapy or radiation. The systemically delivered ligand-liposome-p53 gene therapeutics resulted in efficient expression of functional wild-type p53, sensitizing the tumors to chemotherapy and radiotherapy. This is a novel strategy combining current molecular medicine with conventional chemotherapy and radiotherapy for the treatment of cancer. The systemic delivery of normal tumor suppressor gene p53 by a non-viral, tumor-targeted delivery system as a new therapeutic intervention has the potential to critically impact the clinical management of cancer.

Patterns of wave break during ventricular fibrillation in isolated swine right ventricle

Several different patterns of wave break have been described by mapping of the tissue surface during fibrillation. However, it is not clear whether these surface patterns are caused by multiple distinct mechanisms or by a single mechanism. To determine the mechanism by which wave breaks are generated during ventricular fibrillation, we conducted optical mapping studies and single cell transmembrane potential recording in six isolated swine right ventricles (RV). Among 763 episodes of wave break (0.75 times x s(-1) x cm(-2)), optical maps showed three patterns: 80% due to a wave front encountering the refractory wave back of another wave, 11.5% due to wave fronts passing perpendicular to each other, and 8.5% due to a new (target) wave arising just beyond the refractory tail of a previous wave. Computer simulations of scroll waves in three-dimensional tissue showed that these surface patterns could be attributed to two fundamental mechanisms: head-tail interactions and filament break. We conclude that during sustained ventricular fibrillation in swine RV, surface patterns of wave break are produced by two fundamental mechanisms: head-tail interaction between waves and filament break.

Tp53 gene therapy: a key to modulating resistance to anticancer therapies?

Abnormalities in the p53 tumor suppressor have been identified in over 60% of human cancers. The status of p53 within tumor cells has been proposed to be one of the major determinants of the response to anticancer therapies. In this review we examine the relationship between functional p53 and sensitivity, or resistance, to chemotherapy and radiotherapy. We also discuss the potential of current gene-therapy approaches to restore functional p53 to tumors as a means of modulating the effects of radiation and chemotherapy.

Does p53 status influence tumor response to anticancer therapies?

Abnormalities in the tumor suppressor gene p53 have been identified in over 60% of human cancers. Since it plays such a pivotal role in cell growth regulation and apoptosis, the status of the p53 gene has been proposed as one of the major determinants of a tumor's response to anticancer therapies. In this review we examine the relationship between functional p53 and sensitivity/resistance to both chemotherapy and radiotherapy, and discuss the potential use of some of the current gene therapy approaches to restore functional p53 to tumors as a means of modulating the effects of radiation and chemotherapy.

Are medical students comfortable with practicing physical examinations on each other?

PURPOSE

To assess medical student attitudes toward, and comfort with, taking turns practicing peer physical examinations (PPEs) on fellow classmates.

METHOD

A questionnaire with 25 Likert-scaled questions was administered to 164 end-first-year medical students at the University of Minnesota, Minneapolis. Topics assessed included: (1) comfort with various aspects of PPEs; (2) attitudes regarding the professionalism, appropriateness, and perceived value of PPEs; (3) attitudes toward peer breast, genital, and rectal exams; and (4) the effects of age and gender on response.

RESULTS

Of the 164 students surveyed, 124 (76%) responded. Almost all (98%) agreed that PPEs are appropriate, valuable, and a comfortable experience. Fewer students were comfortable with performing inguinal examinations and conducting PPEs with students of the opposite gender. Twelve percent of the students expressed difficulty in setting limits with peers, and 48% felt exposed when undressed as an examination model in front of a group of peers. The majority of students were opposed to peer breast, genital, and rectal examinations. Some statistically significant gender differences and age/gender interactions were observed.

CONCLUSION

Results suggest that this sample of medical students was very comfortable with PPEs and willing to participate in PPEs, although a few students were uncomfortable with these examinations. No extensive curricular change appears warranted, though steps can be taken to maximize overall student comfort and to accommodate the few students who do not favor PPEs.

Non-viral gene delivery for p53

Abnormality in the tumor suppressor gene p53 is one of the most common occurrences associated with human neoplasia. Consequently, restoration of wild-type p53 function is seen as a particularly promising approach for cancer gene therapy. In recent years, considerable research effort has centered upon developing and improving non-viral delivery systems as alternatives to viral vectors for gene delivery. These methods include the use of lipoplexes and polyplexes, and even delivery of naked DNA. Optimally effective cancer gene therapy requires treatment of metastatic as well as local disease, and to achieve this end, systemic delivery systems for therapeutic genes will be required. This review will discuss some of the recent advances in ways to improve targeting, transfection efficiency and stability for systemic, non-viral p53 gene therapy.

Inhibition of Ras p21 synthesis by antisense undecamers with uniform and specifically arranged phosphorothioate linkages

The design of chimeric oligodeoxynucleotides (ODNs) in which certain phosphodiester linkages are replaced by phosphorothioate (PS) aims to decrease non-sequence-specific effects of uniform PS ODNs and to preserve the PS-provided protection against exo- and endonucleases. This study has, for the fist time, directly compared the differences in nuclease resistance, cellular uptake, antisense potency and sequence specificity of PS and end-capped, pyrimidine-protected (PPS) undecamer ODNs, that are complementary to the initiation codon region of human Ha-ras mRNA. At concentrations above 5 microM, both PS and PPS undecamers were moderately and equally stable for over 48 h in complete medium with RS485 cells overexpressing Ha-ras. They were completely stable at 0.4 microM when complexed with Lipofectin reagent that enhanced cellular uptake up to 9-fold. Both the antisense PPS and PS undecamers produced well-defined inhibition of Ras p21 synthesis in both cell-free and cell-based assays. However, non-sequence-specific effects of the uniform phosphorothioates were still significant. In contrast, the antisense PPS undecamer, when delivered to RS485 cells with Lipofectin reagent, inhibits human Ras p21 synthesis by more than 90% at a concentration of 3.2 microM, while the effect of controls with inverted, mismatched or scrambled sequence was minimal (5% or less) on p21 synthesis and RS485 cell growth.

3'-End conjugates of minimally phosphorothioate-protected oligonucleotides with 1-O-hexadecylglycerol: synthesis and anti-ras activity in radiation-resistant cells

Activation of the ras oncogene has been implicated in many types of human tumors. It has been shown that downmodulation of ras expression can lead to the reversion of the transformed phenotype of these tumor cells. Antisense oligodeoxyribonucleotides (ODNs) can inhibit gene expression by hybridization to complementary mRNA sequences. To minimize toxicity associated with all-phosphorothioated ODNs and improve cellular uptake, we used partially phosphorothioate (PPS)-modified ODNs having an additional hydrophobic tail at the 3'-end (PPS-C(16)). The PPS ODNs are protected against degradation by PS internucleotide linkages at both the 3'- and 5'-ends and additionally stabilized at internal pyrimidine sites, which are the major sites of endonuclease cleavage. Here we show that anti-ras PPS-C(16) ODN retains the high sequence-specificity of PPS ODNs and provides maximal inhibition of Ras p21 synthesis with minimal toxicity even without the use of a cellular uptake enhancer. Moreover, treatment of T24, a radiation-resistant human tumor cell line that carries a mutant ras gene, with anti-ras PPS-C(16) ODN resulted in a reduction in the radiation resistance of the cells in vitro. We also demonstrate that the growth of RS504 (a human c-Ha-ras transformed NIH/3T3 cell line) mouse tumors was significantly inhibited by the combination of intratumoral injection of anti-ras PPS-C(16) ODN and radiation treatment. These findings indicate the potential of this combination of antisense and conventional radiation therapy as a highly effective cancer treatment modality.

Transferrin-liposome-mediated systemic p53 gene therapy in combination with radiation results in regression of human head and neck cancer xenografts

The use of cationic liposomes as nonviral vehicles for the delivery of therapeutic molecules is becoming increasingly prevalent in the field of gene therapy. We have previously demonstrated that the use of the transferrin ligand (Tf) to target a cationic liposome delivery system resulted in a significant increase in the transfection efficiency of the complex [Xu, L., Pirollo, K.F., and Chang, E.H. (1997). Hum. Gene Ther. 8, 467-475]. Delivery of wild-type (wt) p53 to a radiation-resistant squamous cell carcinoma of the head and neck (SCCHN) cell line via this ligand-targeted, liposome complex was also able to revert the radiation resistant phenotype of these cells in vitro. Here we optimized the Tf/liposome/DNA ratio of the complex (LipT) for maximum tumor cell targeting, even in the presence of serum. The efficient reestablishment of wtp53 function in these SCCHN tumor cells in vitro, via the LipT complex, restored the apoptotic pathway, resulting in a significant increase in radiation-induced apoptosis that was directly proportional to the level of exogenous wtp53 in the tumor cells. More significantly, intravenous administration of LipT-p53 markedly sensitized established SCCHN nude mouse xenograft tumors to radiotherapy. The combination of systemic LipT-p53 gene therapy and radiation resulted in complete tumor regression and inhibition of their recurrence even 6 months after the end of all treatment. These results indicate that this tumor-specific, ligand-liposome delivery system for p53 gene therapy, when used in concert with conventional radiotherapy, can provide a new and more effective means of cancer treatment.

[The effect of thermal power plant on microbial ecology and environmental quality]

To investigate the effect of thermal power plant on the microbial ecology and the environmental quality, the Hsieh-Ho Thermal Power Plant was chosen and the populations of microbes including bacteria, actinomycetes, fungi, and cellulolytic, phosphate-solubilizing and nitrogen-fixing microbes were selected as the parameters of microbial ecology. The pH values of the soil sample collected from inside and outside of the plant were 5.2-6.2 and 4.0-5.3, respectively. Moisture content in plant area was lower than that in the surrounding area. Microbial populations of the topsoils were higher than those of the subsoils. Each gram of soil contained 3.64 x 10(4)-5.16 x 10(7) colonies of bacteria, 1.75 x 10(3)-1.10 x 10(6) colonies of actinomycetes and 6.72 x 10(3)-8.78 x 10(6) colonies of fungi in the plant area; while they were 5.52 x 10(4)-2.14 x 10(7), 8.26 x 10(3)-7.25 x 10(5) and 3.49 x 10(3)-2.74 x 10(6) colonies of bacteria, actinomycetes and fungi, respectively, in the surrounding area. The effect of seasonal change on microbial populations was not significant. The ratio of cellulolytic, phosphate-solubilizing and nitrogen-fixing microbes to the total count in the plant area was also higher than that in the surrounding area, and some of them had significant differences. From the statistical analysis, the effect of thermal power generator on the population and distribution of microbes was significantly different.

Restoration of the G1 checkpoint and the apoptotic pathway mediated by wild-type p53 sensitizes squamous cell carcinoma of the head and neck to radiotherapy

BACKGROUND

A significant number of squamous cell carcinomas of the head and neck (SCCHN) resist radiation treatment, the most common form of adjuvant therapy for this disease. The presence of a mutant form of the tumor suppressor gene p53 has been correlated with disruption of programmed cell death (apoptosis) and reduced cell cycle arrest, resulting in increased radiation resistance and survival.

METHODS AND RESULTS

We introduced by means of an adenoviral vector a functional p53 gene into a radiation-resistant SCCHN cell line that harbors mutant p53. Replacement of wild-type p53 restored the G1 block and apoptosis in these cells in vitro. Moreover, introduction of wild-type p53 sensitized SCCHN-induced mouse xenografts to radiotherapy in vivo.

CONCLUSION

The combination of p53 replacement gene therapy with conventional radiotherapy may treat SCCHN more effectively.

p53 mediated sensitization of squamous cell carcinoma of the head and neck to radiotherapy

Radiation resistant squamous cell carcinoma of the head and neck cell line JSQ-3 carries a mutant form of tumor suppressor gene p53. Treatment of these cells with an adenoviral vector containing wild-type p53 (Av1p53) was able to inhibit their growth in vitro and in vivo while having no effect on normal cells. More significantly, introduction of wtp53 also reduced the radiation-resistance level of this cell line in vitro, in a viral dose-dependent manner. Furthermore, this radiosensitization also carried over to the in vivo situation where the response of JSQ-3 cell-induced mouse xenografts to radiotherapy was markedly enhanced after treatment with Av1p53. Complete, long-term regression of the tumors for up to 162 days was observed when a single dose of Av1p53 was administered in combination with ionizing radiation, demonstrating the effectiveness of this combination of gene therapy and conventional radiotherapy. This sensitization of tumors to radiation therapy by replacement of wtp53 could significantly decrease the rate of recurrence after radiation treatment. Since radiation is one of the most prevalent forms of adjunctive therapy for a variety of cancers, these results have great relevance in moving toward an improved cancer therapy.

Transferrin-liposome-mediated p53 sensitization of squamous cell carcinoma of the head and neck to radiation in vitro

Wild-type (wt) p53 DNA was transfected into the radioresistant human cell line JSQ-3, established from a squamous cell carcinoma of the head and neck (SCCHN), using a transferrin-liposome system, and the ability of the introduced wt p53 to sensitize the transfected JSQ-3 cells to ionizing radiation was examined. Transferrin increased the in vitro transfection efficiency of cationic liposomes up to 70-80% in JSQ-3 cells, representing a 6- to 10-fold increase over liposome transfection alone. The exogenous wt p53 was expressed at high levels in transferrin-liposome-DNA-transfected cells and resulted in the reversion of the radioresistant phenotype of the JSQ-3 cells in a DNA dose-dependent manner. The D10 values were reduced from 6.36 +/- 0.54 Gy to 4.13 +/- 0.06 Gy, a value in the radiosensitive range. In vivo, the intratumoral injection of the transferrin-liposome system resulted in a higher number of transfected tumor cells in the JSQ-3 induced nude mouse xenografts when compared with transfection by liposome alone. The results indicate that the combination of p53 replacement gene transduction, mediated by the relatively safe transferrin-liposome system, and conventional ionizing radiation may provide a more effective treatment for head and neck cancer.

Evidence supporting a signal transduction pathway leading to the radiation-resistant phenotype in human tumor cells

A signal transduction pathway, involving oncogenes and their normal counterparts the proto-oncogenes, analogous to that for cell growth and differentiation has been proposed to lead to the phenotype of cellular radioresistance (RR). In this report we provide evidence demonstrating the existence of such a pathway by using antisense oligonucleotides (ASO) to reverse the RR phenotype. Utilizing ASO directed against the raf-1 gene, a central component of this proposed pathway, we were able to reverse the RR phenotype of human tumor cell lines having elevated HER-2 expression or a mutant form of Ha-ras, two genes upstream of raf-1 in signal transduction. Additionally, anti-ras ASO were able to radiosensitize HER-2 overexpressing cells. These results, which verify the presence of a signaling pathway leading to cellular RR, also have possible clinical implications for the use of ASO as a means to sensitize radioresistant tumors to radiation therapy.

Harmonic analysis of homogeneous networks

We introduce a generalization of mutually inhibitory networks called homogeneous networks. Such networks have symmetric connection strength matrices that are circulant (one-dimensional case) or block circulant with circulant blocks (two-dimensional case). Fourier harmonics provide universal eigenvectors, and we apply them to several homogeneous examples: k-wta, k-cluster, on/center off/surround, and the assignment problem. We also analyze one nonhomogeneous case: the subset-sum problem. We present the results of 10000 trials on a 50-node k-cluster problem and 100 trials on a 25-node subset-sum problem.

Cytogenetic response to G2-phase X irradiation in relation to DNA repair and radiosensitivity in a cancer-prone family with Li-Fraumeni syndrome

Noncancerous skin fibroblasts from six family members with Li-Fraumeni syndrome, five with cancer of diverse tissue origin and one with a premalignant neoplasm, showed a high frequency of chromatid aberrations, 94 to 119 breaks and 58 to 95 gaps per 100 metaphase cells arrested with colcemid 0.5 to 1.5 h after X irradiation (1.75 x 10(-2) C/kg). This response results from deficient repair of the radiation-induced DNA damage. In contrast, skin fibroblasts from two unrelated normal controls and a spouse showed 19 breaks and 17 to 19 gaps per 100 cells. Whereas all six members of the cancer-prone family had a radioresistant phenotype, only four had an inherited p53 mutation. Fibroblasts from a radioresistant family member showed the same extent of chromatid damage directly (0 to 0.5 h) after G2-phase X irradiation as those from the radiosensitive control spouse. We conclude, therefore, that radiosensitivity, as determined by cell killing in asynchronous populations of skin fibroblasts, is unrelated to chromosomal sensitivity to G2-phase X irradiation. However, the persistence of a high frequency of chromatid breaks and gaps at 0.5 to 1.5 h after G2-phase X irradiation, a manifestation of deficient DNA repair, is associated with proneness to cancer in this family.

Expression of the c-erbB-2 (HER-2/neu) oncoprotein in human prostatic carcinoma

The objective of this study was to determine the expression of the c-erB-2 oncoprotein via immunohistochemistry of archival clinically localized human prostate cancers and to compare these results to known clinical prognostic factors. In addition, positive staining cases were subjected to differential polymerase chain reaction to assess for c-erbB-2 gene amplification. Immunohistochemical staining with a polyclonal antibody (pAb 1) was performed on archival radical prostatectomy specimens. To standardize the staining, positive and negative control material was generated using c-erbB-2 transfected NIH3T3 cells grown on agar plugs, formalin fixed, paraffin embedded and processed on glass slides for immunohistochemistry. Definite positive membranous staining was detected in 18 of 53 neoplastic cases (34%). In addition, 9 cases of benign prostatic hyperplasia were stained without evidence of c-erbB-2 expression detected. Either focal or diffuse membranous staining was identified in 6 of 27 (22%) well, 8 of 20 (40%) moderately and 4 of 6 (66%) poorly differentiated tumors (p = 0.03, chi-square test for trend). Positive staining occurred in 6 of 18 patients (33%) with pathological stage B and 12 of 33 (36%) with pathological stage C disease. At a mean of 36 months, complete followup was available for 16 of the 18 positive cases and 30 of the 35 negative cases. For stage B 1 of 6 positive (16.7%) versus 1 of 12 negative (8%) staining cases showed progression (p = 1.0). For stage C 7 of 12 positive (58.3%) versus 9 of 21 negative (42.9%) cases showed progression (p = 0.48). Deoxyribonucleic acid was extracted from the exact same archival paraffin blocks for the c-erbB-2 protein positive cases and subjected to differential polymerase chain reaction analysis, which revealed no c-erbB-2 gene amplification. This study demonstrates that approximately a third of all clinically localized prostate cancers express the c-erbB-2 oncoprotein via immunohistochemistry using pAb-1 on archival material, c-erbB-2 oncoprotein expression does not appear to be a prognostic marker for prostate cancer although our results are preliminary and, although oncoprotein expression was detected, no positive case demonstrated deoxyribonucleic acid amplification.

Dominant negative effect of a germ-line mutant p53: a step fostering tumorigenesis

Lysates derived from the fibroblasts of individuals who are homozygous for normal p53 or heterozygous for the germ-line p53 mutation characteristic of certain Li-Fraumeni cancer-prone families were assessed for p53 function utilizing the binding of p53 protein to a p53-specific consensus oligonucleotide sequence. As expected, control nuclear lysates containing only mutant p53 or no p53 displayed little or no such binding. However, the nuclear lysates from heterozygous fibroblasts containing similar amounts of normal p53 and 245D mutant p53 displayed binding that was significantly below 50% of that seen with homozygous wild-type p53 in normal cell lysates. The nuclear lysates of these heterozygous or homozygous fibroblasts exhibited similar levels of DNA binding to a consensus oligonucleotide specific for the transcription factor, AP-1. These results indicate that mutant p53 has a transdominant effect on the binding of DNA by normal p53. These findings also suggest that p53 complexes formed in vivo that contain mutant p53 are functionally impaired even if normal p53 is also present in the complex. The implications of a trans-dominant effect of mutant p53 on the cancer-prone phenotype of individuals heterozygous for mutated p53 in Li-Fraumeni families is discussed.

Several mutant p53 proteins detected in cancer-prone families with Li-Fraumeni syndrome exhibit transdominant effects on the biochemical properties of the wild-type p53

The identification of germ-line mutations in the p53 gene has provided a situation where comparable amounts of wild-type and mutant p53 co-exist in constitutional cells of certain individuals who are cancer-prone. Here we report the biochemical characteristics of several Li-Fraumeni syndrome associated mutant p53 proteins in order to assess the influence of germ-line mutant p53 on the functions of the wild-type p53. Unlike 248W mutant p53 protein, which was previously shown to have no effect on the wild-type p53 conformation (Milner & Medcalf, 1991; Cell 65, 765-774), germ-line associated mutant p53 proteins with residue 133T, 245D or 258K, converted the wild-type p53 conformation into the mutant conformation. Furthermore, lysates containing cotranslated wild-type p53 and these mutant p53 proteins were significantly impaired for DNA and SV40 large T antigen binding. These observations suggest that at least some germ-line p53 mutants might exhibit dominant effects on wild-type p53 functions and, like other mutant p53 proteins, the phenotype of germ-line mt p53 proteins might be variable depending on the particular mutation.

Oncogene- transformed NIH 3T3 cells display radiation resistance levels indicative of a signal transduction pathway leading to the radiation-resistant phenotype

Oncogenes and their normal counterparts, proto-oncogenes, are functionally important cellular genes which interact with one another as components of signal transduction pathways leading to cell growth and differentiation. Numerous reports in the literature have also begun to link these genes to the phenomenon of cellular radiation resistance. In this report we examine the radiation resistance level of NIH 3T3 cells transformed by various oncogenes in an attempt to define the intracellular pathway to the radiation-resistant phenotype. The results demonstrate that an analogous signaling pathway is apparently involved in acquisition of radiation resistance. Serine/threonine protein kinase oncogenes such as raf, mos, and PKC play a central role in the pathway. Moreover, specific oncogenes upstream (sis, HER-2, met, trk, and ras) and downstream (ets and myc) of these important signaling mediators can also influence the radiation resistance level of the cells.

Absent ras gene mutations in human adrenal cortical neoplasms and pheochromocytomas

A variety of human tumors have been studied for ras mutations to date. However, little is known about the prevalence and significance of ras gene activation in adrenal neoplasms. Recently, a study of 10 primary human pheochromocytomas found no evidence for ras mutations. To our knowledge no survey of ras mutations in adrenocortical neoplasms has been reported. Therefore, we analyzed deoxyribonucleic acid (DNA) from 17 archival tumors (8 adrenocortical carcinomas, 6 pheochromocytomas, 2 adrenal adenomas, 1 aldosteronoma, 2 fresh pheochromocytomas and 1 fresh benign adrenal gland) for activating mutations at the 12, 13 and 61 codons of N-ras, H-ras and K-ras. DNA was extracted from archival tissues using 3 different methods: a simplified boiling method, a proteinase-K-phenol chloroform extraction and a novel heat-stable protease Thermus rt41A technique. The boiling and heat-stable protease methods provided for more consistent polymerase chain reaction amplifications than the more laborious phenol chloroform method. This heat-stable protease Thermus rt41A method had not been reported previously for use in archival DNA extraction. Polymerase chain reaction amplified the ras gene regions of interest, and mutations were screened by mutation-specific oligonucleotide probe hybridization of Southern and slot blots. Polymerase chain reaction-generated mutation-specific positive and negative controls were used in the hybridization protocol. With these controlled conditions no definite mutations were detected at codons 12, 13 or 61 of N, H or K-ras. Ras activation via point mutations at these codons rarely, if ever, occurs in adrenal neoplasms.

Altered messenger RNA and unique mutational profiles of p53 and Rb in human esophageal carcinomas

Seventy-nine esophageal carcinoma patients were studied for genetic abnormalities in the p53 and Rb tumor suppressor genes. Single-strand conformation polymorphism analysis and DNA sequencing were used to detect p53 point mutations, Northern blotting was used to examine abnormal expression of p53 and Rb, and polymerase chain reaction and Southern blotting were used to analyze allelic loss. Twenty-five cases were analyzed by DNA sequencing to detect mutations in p53. Fourteen samples contained mutations within exons 5 through 9 of p53; seven had missense mutations giving rise to single amino acid substitutions. The remaining seven (50%) contained nonsense mutations leading to premature termination, five due to single base pair substitutions, and two that were the result of frameshift mutations. In other human tumors, p53 mutations are predominantly missense mutations, but our data as well as those from other groups show that nonsense mutations are common in human esophageal cancer. All but one of the constitutionally heterozygous samples containing mutations also manifested loss of the normal p53 allele; the one exception without allelic loss contained a silent mutation, which should not have had any affect on the p53 protein product. In addition, Northern blotting analysis revealed abnormalities (altered transcript size or mRNA levels) in 5 of 7 cases involving p53 and in 2 of 7 cases analyzed for Rb. Thirty-four cases were informative for allelic loss studies of both p53 and Rb; of these, 25 (74%) lost heterozygosity of p53, Rb, or both. When point mutations and mRNA expression abnormalities were also considered, 33 of 45 (73%) tumors informative for allelic loss assays of both genes as well as for mRNA or point mutation studies showed one or more abnormalities in p53 or Rb. Our results strongly suggest that a unique profile of molecular alterations involving p53 and Rb characterizes human esophageal cancer and that these specific genetic lesions are important in the development and/or progression of most human esophageal carcinomas.

Detection of RAS mutations in archival testicular germ cell tumors by polymerase chain reaction and oligonucleotide hybridization

Preliminary studies of RAS mutational activation in human testicular germ cell neoplasms have yielded conflicting results. Whereas two studies of clinical material revealed a significant incidence of N- and KRAS mutations, two studies of a variety of germ cell lines failed to document RAS mutations. To clarify the incidence of RAS mutations in these tumors, we studied archival paraffin-embedded, formalin-fixed orchiectomy specimens from 25 nonseminomas (NSGCT), 18 seminomas (SEM), and one Leydig cell tumor. For 14 of the 44 neoplasms, DNA was also available from nonmalignant testis adjacent to the tumor. Six age-matched patients had testes removed because of nonmalignant disease and were studied as controls. Polymerase chain reaction (PCR) amplified the K-, N-, and HRAS 12, 13, and 61 codons of these specimens, and mutations were detected with mutation-specific oligonucleotide probe hybridization of Southern and slot blots. Four mutations were found in KRAS 12 (4/44;[9.1%]). One seminoma [1/18(5.6%)] contained the mutation GGT(GLY)----CGT(ARG), and three NSGCT [3/25(12%)] were found to have GGT(GLY)----GAT(ASP) mutations. One of the NSGCT mutations was detected in adjacent nonmalignant tissue, but the corresponding tumor did not contain any detectable mutation. No mutations were detected at KRAS 13 or 61, in NRAS or HRAS 12, 13, or 61, or in the control normal testes. PCR, slot blots, and hybridizations were performed twice by two separate investigators for confirmation of results. PCR-generated mutation-specific positive controls were created for all possible RAS mutations, and these along with wild-type DNA controls were integral to interpretation of the oligonucleotide mismatch hybridization assay. By using positive and negative controls, we have detected a relatively low incidence of RAS mutations in archival human testicular germ cell tumors.

The status of the p53 gene in human papilloma virus positive or negative cervical carcinoma cell lines

We have analyzed p53 gene alterations in five cervical cancer derived cell lines. Two of the five cervical cancer cell lines, HTB31 (C-33A) and 32 (HT-3), harbored missense mutations in codons 273 and 245 respectively, whereas the other three tumor cell lines, HTB33 (ME180), 34 (MS751) and 35 (SIHA), did not reveal any mutation in the p53 coding sequence spanning codons 126-307. Although all the tumor cell lines express comparable levels of p53 RNA, only HTB31 and HTB32 contain high or detectable levels respectively of p53 protein. The other three tumor cell lines, where neither p53 mutation nor the expression of p53 protein could be detected, were found to harbor human papilloma virus (HPV) 16 or 18. The inactivation of the wild-type p53 function resulting from a missense mutation, or the lack of detectable wild-type p53 protein due to the translational/post-translational deregulation of p53 protein levels may be the contributing factor in the tumorigenicity of these five cases of cervical cancer. The lack of detectable p53 protein in HTB33, 34 and 35 associates with the presence of either HPV16 or -18 in these cell lines.

Detection of both mutant and wild-type p53 protein in normal skin fibroblasts and demonstration of a shared 'second hit' on p53 in diverse tumors from a cancer-prone family with Li-Fraumeni syndrome

Germline transmission of mutant p53 gene in cancer-prone families with Li-Fraumeni syndrome has revealed a new role for p53 in the genetic predisposition to cancer. The studies reported here focus on the analysis of the expression of normal and mutant p53 RNA and protein in germline configuration and demonstrate that normal skin fibroblasts derived from members of a family with Li-Fraumeni syndrome express mutant p53Gly----Asp(245) protein and RNA at levels similar to the wild-type p53. Thus, these fibroblasts represent a unique biological system in which endogenous promoters are utilized for the expression of both mutant and normal p53. We have further extended the earlier observations on the analysis of mutant p53 with a limited number of tumors derived from individuals with Li-Fraumeni syndrome. Tumors arising from two different germ layers in four individuals in a single family clearly exhibited the loss of the wild-type allele and the retention of the mutant allele observed in the normal skin fibroblasts derived from the same individuals. These observations further support the notion that germline p53 mutation plays a key role in the tumorigenesis of individuals with Li-Fraumeni syndrome.

Infrequent RAS oncogene mutations in human prostate cancer

The RAS gene family includes three functional genes, H-RAS, K-RAS, and N-RAS, which have been most widely studied in human tumors. Point mutations most commonly occurring at codons 12, 13, or 61 of these genes allow the RAS protooncogene to be converted to a RAS oncogene. A variety of human tumors have been studied for RAS mutations to date, however, conflicting data has been reported regarding prostate cancer. Cell line studies and two American studies of clinical material have found a low incidence of RAS mutation in prostate cancer. The few mutations found were predominantly in the H-RAS gene. Conversely, a recent study of Japanese occult autopsy specimens found an approximate 25% incidence of K-RAS mutations. In this current study, DNA was extracted from 24 archival paraffin-embedded, formalin-fixed radical prostatectomy specimens. Twenty-one of the 24 cases had pathologic stage C disease, and paraffin blocks were selected having the most concentrated area of neoplasm. Twelve, seven, and five cases demonstrated moderate, well and poorly differentiated histologic grade respectively. Polymerase chain reaction (PCR) was used to amplify the K-RAS, N-RAS, and H-RAS 12, 13, 61 codons of these specimens and mutations were detected with mutation-specific oligonucleotide probe hybridization of southern and slot blots. No definite point mutations were detected. PCR's and hybridizations were performed three separate times by three investigators to confirm these results. PCR-generated mutation-specific positive controls and known negative controls were used and found to be important to interpret oligonucleotide hybridization assays. RAS gene mutations appear to be infrequent in clinical prostate carcinomas in American males.

The MspI polymorphism in intron 6 of p53 (TP53) detected by digestion of PCR products

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Antisense inhibition of ras p21 expression that is sensitive to a point mutation

Many genetic disorders result from a single point mutation, and many tumor oncogenes have been found to be altered by a point mutation. The ability to inhibit selectively the expression of the mutated form of a protein without affecting its normal counterpart is central to many therapeutic strategies, since the normal protein may serve indispensable functions. Antisense oligonucleoside methylphosphonates and their psoralen derivatives directed at either normal human Ha-ras p21 or ras p21 that is mutated at a single base in codon 61 have been examined for their efficacy and specificity as inhibitors of p21 expression. Mixed cultures of cells expressing both forms of p21 were treated with the antisense oligomer complementary to the normal p21 or with the antisense oligomer complementary to the point-mutated p21. Each of the antisense oligomers specifically inhibited expression of only the form of ras p21 to which it was completely complementary and left the other form of p21 virtually unaffected.

Dynamics of differentiation in human epidermoid squamous carcinoma cells (A431) with continuous, long-term gamma-IFN treatment

We investigated the long-term effects of continuous gamma interferon (gamma-IFN) treatment on A431, a human squamous carcinoma cell line. Cells were grown in an in vitro culture system, which over time produces cohesive cell masses ("tumoroids") exhibiting three-dimensional, histotypically differentiated structures, e.g., keratin "pearls", intercellular bridges (desmosomes), elongated flattened cells (squames) and stratification. The effects of gamma-IFN on cell growth, morphology and stage of differentiation were assessed at different treatment times by light and electron microscopy and by immunohistochemical staining using antibodies to keratins 1 and 14 and to filaggrin, markers of specific stages of keratinocyte differentiation. Our results show that A431 cells have the capacity for spontaneous differentiation, that this capacity is significantly enhanced and accelerated by gamma-IFN treatment leading to terminal differentiation and extensive cell death by 2 wk. Despite continuous exposure to IFN, a small number of viable, undifferentiated cells remain. Their proliferation, evident by 3 wk, reconstitutes the tumoroid which once again contains the full range of differentiating cell types.

Aberrant DNA topoisomerase II activity, radioresistance and inherited susceptibility to cancer

Inherited susceptibility to a wide variety of neoplasias (Li-Fraumeni syndrome), has been shown in studies of one cancer-prone family, to have an intriguing association with an aberrant c-raf-1 gene and inheritance of a radioresistant phenotype in their non-cancerous skin fibroblasts. This association together with observations that DNA topoisomerases, when defective, can introduce errors into DNA and that these enzymes are perturbed in vitro by serine/threonine kinases similar to raf encoded proteins, prompted investigation of DNA topoisomerase activity of the family's fibroblasts. Since radioresistance was transferred to murine cells (NIH-3T3) when the aberrant c-raf-1 gene from this family was transfected, we also examined transformants containing this and other oncogenes. V-raf/c-myc and EJ-ras transformants were examined, the former because the family's skin fibroblasts also have 3-8-fold elevated myc expression (not apparently relevant to radioresistance) and the latter because ras, like raf, conveys radioresistance. The family members' fibroblasts and the three transfected murine lines, showed a similar perturbation of a spermidine and ATP-dependent DNA catenation activity (typical of DNA topoisomerase II). There was a significant positive correlation (r = 0.93; P = 0.0026) between the degree of activation of topoisomerase II and one measure of radioresistance (the Dq value). Relaxation of DNA supercoiling (topoisomerase I activity and other DNA nicking enzymes) was not abnormal. Cytotoxicity assays and evaluation of the influence of topoisomerase II inhibitors on DNA/protein complex formation, corroborated the existence of a qualitative topoisomerase II defect in the family's cells and transfectants. Although the contention that the qualitative topoisomerase II abnormalities observed here may be associated with malfunction is highly speculative, these findings may be relevant to the mechanism of oncogenesis, not only in this family, but with raf and ras type oncogenes.

Germ-line transmission of a mutated p53 gene in a cancer-prone family with Li-Fraumeni syndrome

Tumour suppressor genes, whose usual function seems to be controlling normal cell proliferation, have been implicated in many inherited and sporadic forms of malignancies Much evidence supports the concept of tumour formation by loss-of-function mutations in suppressor genes, as predicted by the two-hit model of Knudson and DeMars. The suppressor gene, p53, is affected in such a manner by numerous mutations, which occur in a variety of human tumours. These mutations usually represent the loss of one allele and the substitution of a single base in the other. We have now analysed the p53 gene in a family affected by Li-Fraumeni syndrome, a rare autosomal dominant syndrome characterized by the occurrence of diverse mesenchymal and epithelial neoplasms at multiple sites. In some instances the neoplasms seem to be related to exposure to carcinogens, including ionizing radiation. The Li-Fraumeni family that we studied had noncancerous skin fibroblasts (NSF) with an unusual radiation-resistant phenotype. DNA derived from the NSF cells of four family members, spanning two generations, had the same point mutation in codon 245 (GGC----GAC) of the p53 gene. This mutation leads to substitution of aspartic acid for glycine in one of the regions identified as a frequent target of point mutations in p53. The NSF cell lines with the mutation also retained the normal p53 allele. This inherited p53 mutation may predispose the members of this family to increased susceptibility to cancer.

Phase I-II study of advanced head and neck squamous cell carcinoma patients treated with recombinant human interferon gamma

The association of immunodeficiency with head and neck squamous cell carcinoma has generated the concept of supplying immunologically active agents as a means of treating these cancers. One of the most active immunologic messengers is interferon gamma, which has been observed in our laboratories to also have a direct cytotoxic effect on cultures of squamous cell carcinoma derived from the head and neck. To test the feasibility of treating patients with advanced but resectable head and neck cancer with this agent, we designed a phase I-II trial of recombinant human interferon gamma using a 24-hour infusion repeated weekly for four times. In this study, both tumor and immunologic parameters were studied before and after treatment. Eight patients were entered into the study with the highest recombinant human interferon gamma dose attempted being 0.25 mg/m2 per 24 hours. Minimal side effects were observed. Three patients had clinically measurable responses, four had stabilization of disease, and one had progression while receiving treatment. Histopathologic results of treatment were similar to in vitro observations. Necrosis, as well as differentiation of tumor cells, was observed. In some tumors there was a marked decrease in cellularity without a change in tumor volume due to increased extracellular keratin deposition. Our study indicates that evaluation of adoptive immunotherapy trials in head and neck cancer needs to include parameters other than simple tumor regression as an end point, otherwise therapeutically important lymphokine-induced changes may be missed. Further evaluation of recombinant human interferon gamma and agents that induce human interferon gamma are warranted.

Comparative inhibition of ras p21 protein synthesis with phosphorus-modified antisense oligonucleotides

A rabbit reticulocyte lysate translation assay was used to quantitatively compare a series of antisense oligodeoxyribonucleotides (11-mers) having different internucleoside linkages and various degrees of complementarity (100-80%) with the start codon and downstream 8 bases of Balb-ras p21 mRNA. The oligomers had either contiguous phosphodiester, or alternating methylphosphonate-phosphodiester, or contiguous methylphosphonate, or contiguous phosphorothioate linkages. Under the conditions used for the assay, all of the test compounds when present in about 10(3)-10(4) excess over mRNA (15 nM mRNA) inhibited protein synthesis to a degree which was dependent on both the concentration and sequence of the oligomer. At low concentrations (12.5-25 microM), the phosphorothioate analogs were the most potent inhibitors of p21 protein synthesis; however, a sequence non-specific effect for these oligomers was dominant at higher concentrations of oligomer (100-200 microM). The methylphosphonate oligomers appeared to be slightly more discriminant. Relative hybridization strengths were assessed by melting (Tm) studies using a DNA oligomer target to mimic the mRNA.

raf involvement in the simultaneous genetic transfer of the radioresistant and transforming phenotypes

We examined a human Alu+ mouse tertiary transformant derived from a noncancerous skin fibroblast cell line which exhibits the unique characteristic of being resistant to the killing effects of ionizing radiation. This transformed cell line was found to contain activated human c-raf-1, and demonstrated an increased level of radioresistance indicating the simultaneous transfer of both the transforming and radiation-resistant phenotypes. We have also found a relationship between the presence of activated oncogenes, specifically those with serine/threonine kinase activity and the radioresistant phenotype.

A study of the bronchial provocation test with methacholine in patients with active pulmonary tuberculosis

Bronchial hyperreactivity is a characteristic feature of bronchial asthma. Recent respiratory infections, allergic rhinitis, atopic family history, pulmonary tuberculosis, pulmonary sarcoidosis, cystic fibrosis, and farmer's lung have also been demonstrated to have bronchial hyperreactivity to inhaled methacholine. It is not known if pulmonary tuberculosis can cause nonspecific bronchial hyperreactivity and what the mechanism would be. We therefore undertook to evaluate nonspecific bronchial hyperreactivity in active pulmonary tuberculosis using the bronchial provocation test with methacholine and we measured the total serum IgE and peripheral eosinophil count to seek some mechanisms. There were 5 patients among 18 subjects with active pulmonary tuberculosis whose response to methacholine was positive. The mean baseline FEV1 of positive responders was 71.40 +/- 17.39%, and that of negative responders was 110.18 +/- 17.65% (p less than 0.05). There were no significant differences in serum IgE and peripheral eosinophil count between positive and negative responders. We found that active pulmonary tuberculosis would increase the nonspecific bronchial response with methacholine, and the mechanism of the bronchial hyperreactivity in patients with active pulmonary tuberculosis may not be related to an immunologic mechanism but may be related to the stimulating receptors.

Association of interferon-gamma induced growth inhibition and modulation of epidermal growth factor receptor gene expression in squamous cell carcinoma cell lines

Interferons (IFN) possess the ability to inhibit proliferation of certain transformed cell lines. Down modulation of the abnormal expression of certain oncogenes by IFN has been associated with phenotypic reversion of src, myc, or ras transformed cells. It has already been shown that some squamous cell carcinoma (SCCa) cell lines express elevated levels of the epidermal growth factor receptor (EGFR). Previously, in A431, an SCCa cell line, it was shown that IFN-gamma-induced growth inhibition was associated with both enhanced expression of EGFR and terminal differentiation. This study examines the effect of IFN-beta or IFN-gamma on five additional cervical SCCa cell lines. One cell line was shown to have amplification of the EGFR gene. An IFN-gamma induced antiproliferative response, observed in four of the five cell lines, was associated with increased expression of EGFR mRNA and induction of the IFN-inducible genes, HLA-A3 class I antigen and 2-5 oligoadenylate synthetase. These data suggest that the increased expression of the EGFR gene in a particular SCCa may predict response to IFN-gamma.